Investigation of a new Cu,Zn superoxide dismutase mutant: the Thr-->Arg 137 derivative.
Biochemistry
; 32(16): 4384-8, 1993 Apr 27.
Article
em En
| MEDLINE
| ID: mdl-8386544
ABSTRACT
The preparation and biophysical characterization of a mutant of superoxide dismutase in which the native Thr 137 has been substituted with a positive Arg residue are reported. Thr 137 forms, together with Arg 143, a bottleneck at the entrance to the active-site Cu ion. The geometry of the Cu ligands shows only minor changes after the above substitution. However, the enzymatic activity of the Arg 137 mutant is smaller than that of the wild type at physiological ionic strength and approaches that of wild type in the limit of zero ionic strength. The binding constant of the anion N3-, which had previously been shown to be a good probe of the O2- substrate, is increased about 20-fold in the mutant with respect to the value found in the wild type. These results are discussed on the bases of the whole charge of the cavity and the possible change in the conformation of the active-site channel.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Arginina
/
Conformação Proteica
/
Superóxido Dismutase
/
Treonina
/
Mutagênese Sítio-Dirigida
Limite:
Humans
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
1993
Tipo de documento:
Article
País de afiliação:
Itália